Edited with Introductory Essay by
Kent Roberts Greenfield
OFFICE OF THE CHIEF OF MILITARY HISTORY
DEPARTMENT OF THE ARMY
WASHINGTON, D.C., 1960
Library of Congress Catalog Card Number: 59-60007
On 6 August 1945 the United States exploded an atomic bomb over Hiroshima and revealed to the world in one blinding flash the start of the atomic age. As the meaning of this explosion and the nature of the force unleashed became apparent, a chorus of voices rose in protest against the decision that opened the Pandora's box of atomic warfare.
The decision to use the atomic bomb was made by President Truman. There was never any doubt of that and despite the rising tide of criticism Mr. Truman took full responsibility for his action. Only recently succeeded to the Presidency after the death of Roosevelt and beset by a multitude of problems of enormous significance for the postwar world, Mr. Truman leaned heavily on the advice of his senior and most trusted advisers on the question of the bomb. But the final decision was his and his alone. 
The justification for using the atomic bomb was that it ended the war, or at least ended it sooner and thereby saved countless American-and Japanese-lives. But had it? Had not Japan been defeated and was she not already on the verge of surrender? What circumstances, it was asked, justified the fateful decision that "blasted the web of history and, like the discovery of fire, severed past from present"? 
The first authoritative explanation of how and why it was decided to use the bomb came in February 1947 from Henry L. Stimson, wartime Secretary of War and the man who more than any other was responsible for advising the President in this matter.  This explana-
 The study that follows was published in substantially its present form in Foreign Affairs, Vol. XXV, No. 2 (January, 1957). It is reprinted by special permission from Foreign Affairs; copyright by Council on Foreign Relations, New York.  James Phinney Baxter, 3rd, Scientists Against Time (Boston: Little, Brown and Company, 1946), p. 419.  Henry L. Stimson, "The Decision To Use the Atomic Bomb," Harper's Magazine (February, 1947). The article is reproduced with additional comments in Henry L. Stimson and McGeorge Bundy, On Active Service in Peace and War (New York: Harper & Brothers, 1948), Chapter XIII, and in Bulletin of the Atomic Scientists, Vol. III, No. 2 (February, 1947).
tion did not answer all the questions or still the critics. During the years that have followed others have revealed their part in the decision and in the events shaping it. These explanations have not ended the controversy but they have brought to light additional facts bearing on the decision to use the bomb.
The epic story of the development of the atomic bomb is well known.  It began in 1939 when a small group of eminent scientists in this country called to the attention of the United States Government the vast potentialities of atomic energy for military purposes and warned that the Germans were already carrying on experiments in this field. The program initiated October of that year with a very modest appropriation and later expanded into the two-billion-dollar Manhattan Project had only one purpose-to harness the energy of the atom in a chain reaction to produce a bomb that could be carried by aircraft if possible, and to produce it before the Germans could.  That such a bomb, if produced, would be used, no responsible official ever questioned. "At no time from 1941 to 1945," declared Mr. Stimson, "did I ever hear it suggested by the President, or by another responsible member of the Government, that atomic energy should not be used in that war." And Dr. J. Robert Oppenheimer recalled in 1954 that "we always assumed if they [atomic bombs] were needed, they would be used." 
So long as the success of the project remained in doubt there seems to have been little or no discussion of the effects of an atomic weapon or the circumstances under which it would be used. "During the
 The best semitechnical account of the development of the bomb is by H. D. Smyth, A General Account of the Development of Methods of Using Atomic Energy for Military Purposes ... (Washington, 1945). An excellent short account is in Baxter, Scientists Against Time, pp. 419-50. The best popular accounts are W. L. Laurence, Dawn Over Zero (New York: Alfred A. Knopf, 1946) and J. W. Campbell, The Atomic Story (New York: Henry Holt and Company, 1947). For a graphic account of the establishment of the Los Alamos Laboratory, see the testimony of Dr. J. Robert Oppenheimer in U.S. Atomic Energy Commission, Transcript of Hearings Before Personnel Security Board in the Matter of Dr. J. Robert Oppenheimer, 12 April-6 May 1954 (Washington, 1954), pp. 12-15, 28-29. For a vivid account of the bombing see Merle Miller and Abe Spitzer, We Dropped the A-Bomb (New York: Thomas Y. Crowell Company, 1946), and Laurence, Dawn Over Zero, pp. 207-11. The one exception was the Navy's work in the field of atomic energy as a source of power for naval vessels, Hearings Before the Special Committee on Atomic Energy, 79th Cong., 1st Sess., Senate, S.R. 179, Part 3, pp. 364-89, testimony of Dr. Ross Gunn.  Stimson, "The Decision to Use the Atomic Bomb," Harper's, p. 98; Oppenheimer Hearings, p. 33.
early days of the project," one scientist recalled, "we spent little time thinking about the possible effects of the bomb we were trying to make."  It was a "neck-and-neck race with the Germans," the outcome of which might well determine who would be the victor in World War II. But as Germany approached defeat and as the effort to produce an atomic bomb offered increasing promise of success, those few men who knew what was being done and who appreciated the enormous implications of atomic energy became more and more concerned. Most of this concern came from the scientists in the Metallurgical Laboratory in Chicago, where by early 1945 small groups began to question the advisability of using the weapon they were trying so hard to build.  It was almost as if they hoped the bomb would not work after it was completed.
On the military side, realization that a bomb would probably be ready for testing in the summer of 1945 led to concrete planning for the use of the new weapon, on the assumption that the bomb when completed would work. By the end of 1944 a list of possible targets in Japan had been selected, and a B-29 squadron was trained for the specific job of delivering the bomb.  It was also necessary to inform certain commanders in the Pacific about the project, and on 30 December 1944 Maj. Gen. Leslie R. Groves, head of the Manhattan District, recommended that this be done. 
Even at this stage of development no one could estimate accurately when the bomb would be ready or guarantee that, when ready, it would work. It is perhaps for this reason-and because of the complete secrecy surrounding the project-that the possibility of an atomic weapons never entered into the deliberations of the strategic planners. It was, said Admiral William D. Leahy, "the best kept secret of the entire war" and only a handful of the top civilian and military officials in Washington knew about the bomb.  As a matter of fact, one
 Hearing Before the Special Committee on Atomic Energy, Part 2, p. 302, testimony of Dr. John A. Simpson.  Ibid., p. 303; Oppenheimer Hearings, p. 33, Leo Slizard, "A Personal History of the Bomb," The Atlantic Community Faces the Bomb, University of Chicago Roundtable 601, September 25, 1949, p. 14; Arthur H. Compton, Atomic Quest (New York: Oxford University Press, Inc., 1956); Alice Kimball Smith, "Behind the Decision to Use the Atomic Bomb: Chicago 1944-45," Bulletin of Atomic Scientists, XIV, No. 8 (October, 1958), pp. 288-312.  Wesley Frank Craven and James Lea Cate, eds., The Army Forces in World War II, Vol. V, The Pacific, Matterhorn to Nagasaki (Chicago: The University of Chicago Press, 1953), pp. 705-08.  Memo, Groves for CofS, 30 Dec 44, sub: Atomic Fission Bombs, printed in Foreign Relations of the United States: The Conferences at Malta-Yalta, 1945 (Washington, 1955) (hereafter cited as Malta-Yalta Conferences).  Fleet Admiral William D. Leahy, I Was There (New York: Whittlesey House, 1950), p. 434.
bright brigadier general who innocently suggested that the Army might do well to look into the possibilities of atomic energy suddenly found himself the object of the most intensive investigation.  So secret was the project, says John J. McCloy, that when he raised the subject at a White House meeting of the Joint Chiefs of Staff in June 1945 it "caused a sense of shock even among that select group."  It was not until March 1945 that it became possible to predict with certainty that the bomb would be completed in time for testing in July. On March 15, Mr. Stimson discussed the project for the last time with President Roosevelt, but their conversation dealt mainly with the effects of the use of the bomb, not with the question of whether it ought to be used.  Even at this late date, there does not seem to have been any doubt at the highest levels that the bomb would be used against Japan if it would help bring the war to an early end. But on lower levels, and especially among the scientists at the Chicago laboratory, there was considerable reservation about the advisability of using the bomb. 
After President Roosevelt's death, it fell to Stimson to brief the new President about the atomic weapon. At a White House meeting on 25 April, he outlined the history and status of the program and predicted that "within four months we shall in all probability have completed the most terrible weapon ever known in human history."  This meeting, like Stimson's last meeting with Roosevelt, dealt largely with the political and diplomatic consequences of the use of such a weapon rather than with the timing and manner of employment, the circumstances under which it would be used, or whether it would be used at all. The answers to these questions depended on factors not yet known. But Stimson recommended, and the President approved, the appointment of a special committee to consider them. 
 Ray S. Cline, Washington Command Post: The Operations Division, UNITED STATES ARMY IN WORLD WAR II (Washington, 1951), pp. 347, 348n.  John J. McCloy, The Challenge to American Foreign Policy (Cambridge: Harvard University Press, 1953), p. 42. See also Fleet Admiral Ernest J. King and Walter Muir Whitehill, Fleet Admiral King (New York: Norton, 1952), pp. 620-21; James F. Byrnes, Speaking Frankly (New York: Harper & Brothers, 1947), p. 257.  Stimson, "The Decision To Use the Atomic Bomb," Harper's, page 98, prints the memorandum Stimson prepared on this conversation; King and Whitehill, Fleet Admiral King, page 621, indicates the status of the project and the optimism of the period. See also, Byrnes, Speaking Frankly, p. 258.  Hearings, Before the Special Committee on Atomic Energy, Part 2, p. 303ff, testimony of Dr. Simpson.  His memorandum of this meeting is printed in Stimson, "The Decision To Use the Atomic Bomb," Harper's pages 99-100.  Ibid., Harry S. Truman, Memoirs, Vol. I, Year of Decisions (Garden City, N.Y.: Doubleday and Company, Inc., 1955), pp. 10-11; William Hillman, ed., Mr. President (New York: Farrar, Straus, 1952), p. 249; Byrnes, Speaking Frankly, p. 259. President Truman actually first learned about the bomb from Byrnes.
This special committee, known as the Interim Committee, played a vital role in the decision to use the bomb. Secretary Stimson was chairman, and George L. Harrison, President of the New York Life Insurance Company and special consultant in the Secretary's office, took the chair when he was absent. James F. Byrnes, who held no official position at the time, was President Truman's personal representative. Other members were Ralph A. Bard, Under Secretary of the Navy, William L. Clayton, Assistant Secretary of State, and Drs. Vannevar Bush, Karl T. Compton, and James B. Conant. Generals Marshall and Groves attended at least one and possibly more of the meetings of the committee. 
The work of the Interim Committee, in Stimson's words, "ranged over the whole field of atomic energy, in its political, military, and scientific aspects."  During the first meeting the scientific members reviewed for their colleagues the development of the Manhattan Project and described vividly the destructive power of the atomic bomb. They made it clear also that there was no known defense against this kind of attack. Another day was spent with the engineers and industrialists who had designed and built the huge plants at Oak Ridge and Hanford. Of particular concern to the committee was the question of how long it would take another country, particularly the Soviet Union, to produce an atomic bomb. "Much of the discussion," recalled Dr. Oppenheimer who attended the meeting of 1 June as a member of a scientific panel, "revolved around the question raised by Secretary Stimson as to whether there was any hope at all of using this development to get less barbarous relations with the Russians." 
The work of the Interim Committee was completed 1 June 1945,  when it submitted its report to the President, recommending unanimously that:
1. The bomb should be used against Japan as soon as possible.
2. It should be used against a military target surrounded by other buildings.
3. It should be used without prior warning of the nature of the weapon. (One member, Ralph A. Bard, later dissented from this portion of the committee's recommendation.)
 Stimson, "The Decision To Use the Atomic Bomb," Harper's, p. 100; Byrnes, Speaking Frankly, p. 259; Oppenheimer Hearings, p. 34; Smith, "Behind the Decision To Use the Atomic Bomb: Chicago 1944-45," Bulletin of Atomic Scientists, pp. 296-97.  Stimson, "The Decision To Use the Atomic Bomb," Harper's, p. 100.  Oppenheimer Hearings, pp. 34, 257, testimony of Drs. Oppenheimer and Compton; Byrnes, Speaking Frankly, pp. 260-61; Stimson, "The Decision To Use the Atomic Bomb," Harper's, pp. 100-101.  Stimson "The Decision To Use the Atomic Bomb," Harper's, p. 101; Truman, Year of Decisions, p. 419. Byrnes mistakenly states that the Interim Committee made its recommendations on 1 July. Byrnes, Speaking Frankly.
"The conclusions of the Committee," wrote Stimson, "were similar to my own, although I reached mine independently. I felt that to extract a genuine surrender from the Emperor and his military adviser s, they must be administered a tremendous shock which would carry convincing proof of our power to destroy the empire. Such an effective shock would save many times the number of lives, both American and Japanese, than it would cost." 
Among the scientists working on the Manhattan Project were many who did not agree. To them, the "wave of horror and repulsion" that might follow the sudden use of an atomic bomb would more than outweigh its military advantages. "It may be very difficult," they declared, "to persuade the world that a nation which was capable of secretly preparing and suddenly releasing a new weapon, as indiscriminate as the rocket bomb and a thousand times more destructive, is to be trusted in its proclaimed desire of having such weapons abolished by international agreement."  The procedure these scientists recommended was, first, to demonstrate the new weapon "before the eyes of representatives of all the United Nations on the desert or a barren island," and then to issue "a preliminary ultimatum" to Japan. If this ultimatum was rejected, and "if sanction of the United Nations (and of public opinion at home) were obtained," then and only then, said the scientists, should the United States consider using the bomb. "This may sound fantastic," they said, "but in nuclear weapons we have something entirely new in order of magnitude of destructive power, and if we want to capitalize fully on the advantage their possession gives us, we must use new and imaginative methods." 
These views, which were forwarded to the Secretary of War on 11 June 1945, were strongly supported by sixty-four of the scientists in the Chicago Metallurgical Laboratory in a petition sent directly to the President. At about the same time, at the request of Dr. Arthur H. Compton, a poll was taken of the views of more than a hundred and fifty scientists at the Chicago Laboratory. Five alternatives ranging from all-out use of the bomb to "keeping the existence of the bomb a secret" were presented. Of those polled, about two thirds voted for
 Stimson, "The Decision To Use the Atomic Bomb," Harper's, p. 101. The same idea is expressed by Winston S. Churchill, Triumph and Tragedy (Cambridge: Houghton Mifflin Company, 1953), p. 638-39.  "Report of the Committee on Social and Political Implications," signed by Professor James Franck of the University of Chicago and submitted to the Secretary of War, 11 June 1945, Bulletin of Atomic Scientists, Vol. 1, No. 10 (May 1, 1946), p. 3; Smith, "Behind the Decision to Use the Atomic Bomb: Chicago 1944-45," Bulletin of Atomic Scientists, pp. 299-302.  Ibid, pp. 3-4.
a preliminary demonstration, either on a military objective or an uninhabited locality; the rest were split on all-out use and no use at all.
These views, and presumably others, were referred by Secretary Stimson to a distinguished Scientific Panel consisting of Drs. Arthur H. Compton, Enrico Fermi, E. O. Lawrence, and J. Robert Oppenheimer, all nuclear physicists of the first rank. "We didn't know beans about the military situation," Oppenheimer later said. "We didn't know whether they [the Japanese] could be caused to surrender by other means or whether the invasion [of Japan] was really inevitable.... We thought the two overriding considerations were the saving of lives in the war and the effect of our actions on the stability of the post-war world."  On 16 June the panel reported that it had studied carefully the proposals made by the scientists but could see no practical way of ending the war by a technical demonstration. Almost regretfully, it seemed, the four members of the panel concluded that there was "no acceptable alternative to direct military use."  "Nothing would have been more damaging to our effort," wrote Stimson, "than a warning or demonstration followed by a dud-and this was a real possibility." With this went the fear expressed by Byrnes, that if the Japanese were warned that an atomic bomb would be exploded over a military target in Japan as a demonstration, "they might bring our boys who were prisoners of war to that area."  Furthermore, only two bombs would be available by August, the number General Groves estimated would be needed to end the war; these two would have to obtain the desired effect quickly. And no one yet knew, nor would the scheduled ground test in New Mexico prove, whether a bomb dropped from an airplane would explode. 
Nor, for that matter, were all those concerned certain that the bomb would work at all, on the ground or in the air. Of these doubters, the greatest was Admiral Leahy, who until the end remained unconvinced. "This is the biggest fool thing we have ever done," he told Truman after Vannevar Bush had explained to the President how the bomb worked. "The bomb will never go off, and I speak as an expert in explosives." 
 Ibid., p. I; Szilard, "A Personal History of the Bomb," University of Chicago Roundtable 601, p. 15. See also P. M. S. Blackett, Fear, War, and the Bomb (New York: Whittlesey House, 1949), pp. 114-16.  Oppenheimer Hearings, p. 34.  Quoted in Stimson, "The Decision To Use the Atomic Bomb," Harper's, p. 101. The Scientific Panel was established to advise the Interim Committee and its report was made to that body.  Ibid.; Byrnes, Speaking Frankly, p. 261.  Ibid.; Oppenheimer Hearings, p. 163, testimony of General Groves.  Truman, Year of Decisions, p. 11. Leahy in his memoirs frankly admits this error.
President's civilian advisers on the use of the bomb. The arguments of the opponents had been considered and rejected. So far as is known, the President did not solicit the views of the military or naval staffs, nor were they offered.
The military situation on 1 June 1945, when the Interim Committee submitted its recommendations on the use of the atomic bomb, was distinctly favorable to the Allied cause. Germany had surrendered in May and troops from Europe would soon be available for redeployment in the Pacific. Manila had fallen in February; Iwo Jima was in American hands; and the success of the Okinawa invasion was assured. Air and submarine attacks had all but cut off Japan from the resources of the Indies, and B-29's from the Marianas were pulverizing Japan's cities and factories. The Pacific Fleet had virtually driven the Imperial Navy from the ocean, and planes of the fast carrier forces were striking Japanese naval bases in the Inland Sea. Clearly, Japan was a defeated nation.
Though defeated in a military sense, Japan showed no disposition to surrender unconditionally. And Japanese troops had demonstrated time and again that they could fight and inflict heavy casualties even when the outlook was hopeless. Allied plans in the spring of 1945 took these facts into account and proceeded on the assumption that an invasion of the home islands would be required to achieve at the earliest possible date the unconditional surrender of Japan-the announced objective of the war and the first requirement of all strategic planning. 
Other means of achieving this objective had been considered and, in early June, had not yet been entirely discarded. One of these called for the occupation of a string of bases around Japan to increase the intensity of air bombardment. Combined with a tight naval blockade, such a course would, many believed, produce the same results as an invasion and at far less cost in lives.  "I was unable to see any justification," Admiral Leahy later wrote, "for an invasion of an already thoroughly defeated Japan. I feared the cost would be enormous in
 For an account of the strategic plans evolved for the defeat of Japan, see The Entry of the Soviet Union Into the War Against Japan: Military Plans, 1941-1945 (Department of Defense Press Release, September 1955), pp. 28, 62-67, and passim, Cline, Washington Command Post, Ch. XVII; Leahy, I Was There, pp. 383-85; Craven and Cate, The Army Air Forces in World War II, Vol. V, p. 702, and passim.  The alternatives to invasion were outlined by General Marshall for MacArthur in a message of 12 April 1945, reproduced in The Entry of the Soviet Union Into the War Against Japan, pp. 54-55.Page 501
both lives and treasure." Admiral King and other senior naval officers agreed. To them it had always seemed, in King's words, "that the defeat of Japan could be accomplished by sea and air power alone, without the necessity of actual invasion of the Japanese home islands by ground troops. " 
The main arguments for an invasion of Japan-the plans called for an assault against Kyushu (OLYMPIC) on 1 November 1945, and against Honshu (CORONET) five months later-are perhaps best summarized by General Douglas MacArthur. Writing to the Chief of Staff on 20 April 1945, he declared that this course was the only one that would permit application of the full power of our combined resources-ground, naval, and air-on the decisive objective. Japan, he believed, would probably be more difficult to invade the following year. An invasion of Kyushu at an early date would, moreover, place United States forces in the most favorable position for the decisive assault against Honshu in 1946, and would "continue the offensive methods which have proved so successful in Pacific campaigns."  Reliance upon bombing alone, MacArthur asserted, was still an unproved formula for success, as was evidenced by the bomber offensive against Germany. The seizure of a ring of bases around Japan would disperse Allied forces even more than they already were, MacArthur pointed out, and (if an attempt was made to seize positions on the China coast) might very well lead to long-drawn-out operations on the Asiatic mainland.
Though the Joint Chiefs had accepted the invasion concept as the basis for preparations, and had issued a directive for the Kyushu assault on 25 May, it was well understood that the final decision was yet to be made. By mid-June the time had come for such a decision and during that period the Joint Chiefs reviewed the whole problem of Japanese strategy. Finally, on 18 June, at a meeting in the White House, they presented the alternatives to President Truman. Also present (according to the minutes) were Secretaries Stimson and James V. Forrestal and Assistant Secretary of War John J. McCloy. 
General Marshall presented the case for invasion and carried his colleagues with him, although both Admirals Leahy and King later
 Leahy, I Was There, pp. 384-85; King and Whitehill, Fleet Admiral King, p. 598. See also H. H. Arnold, Global Mission (New York: Harper & Brothers, 1949), pp. 595-96; Major General Charles A. Willoughby and John Chamberlain, MacArthur, 1941-1951 (New York: McGraw-Hill, 1954), pp. 287-88.  This message is reproduced in The Entry of the Soviet Union Into the War Against Japan, pp. 55-57.  For a summary of this meeting, see The Entry of the Soviet Union Into the War Against Japan, pp. 77 85. See also, McCloy, Challenge to American Foreign Policy, pp. 42-43; Walter Millis, ed., The Forrestal Diaries (New York: Viking Press, 1951), pp. 70-71; Leahy, I Was There, pp. 383-85; King and Whitehill, Fleet Admiral King, pp. 598, 605-06.
declared they did not favor the plan. After considerable discussion of casualties and of the difficulties ahead, President Truman made his decision. Kyushu would be invaded as planned and preparations for the landing were to be pushed through to completion. Preparations for the Honshu assault would continue, but no final decision would be made until preparations had reached the point "beyond which there would not be opportunity for a free choice."  The program thus approved by Truman called for:
1. Air bombardment and blockade of Japan from bases in Okinawa, Iwo Jima, the Marianas, and the Philippines.
2. Assault of Kyushu on 1 November 1945, and intensification of blockade and air bombardment.
3. Invasion of the industrial heart of Japan through the Tokyo Plain in central Honshu, tentative target date 1 March 1946. 
During the White House meeting of June 18, there was discussion of the possibility of ending the war by political means. The President displayed a deep interest in the subject and both Stimson and McCloy emphasized the importance of the "large submerged class in Japan who do not favor the present war and whose full opinion and influence had never yet been felt."  There was discussion also of the atomic bomb, since everyone present knew about the bomb and the recommendations of the Interim Committee. The suggestion was made that before the bomb was dropped, the Japanese should be warned that the United States had such a weapon. "Not one of the Chiefs nor the Secretary," recalled M0r. McCloy, "thought well of a bomb warning, an effective argument being that no one could be certain, in spite of the assurances of the scientists, that the 'thing would go off.'" 
Though the defeat of the enemy's armed forces in the Japanese homeland was considered a prerequisite to Japan's surrender, it did not follow that Japanese forces elsewhere, especially those on the Asiatic mainland, would surrender also. It was to provide for just this contingency, as well as to pin down those forces during the invasion of
 McCloy, Challenge to American Foreign Policy, p. 41. See also sources cited in preceding note.  The Entry of the Soviet Union Into the War Against Japan, p. 90; Leahy, I Was There, p. 385; King and Whitehill, Fleet Admiral King, p. 606; Malta-Yalta Conferences, pp. 388-400, 827-32.  The Entry of the Soviet Union Into the War Against Japan, p. 83; Joseph C. Grew, The Turbulent Era, edited by Walter Johnson, 2 vols. (Boston: Houghton Mifflin Company, 1952), Ch. XXXVI; McCloy, Challenge to American Foreign Policy, pp. 42-43; Ltr, McCloy to Hamilton Fish Armstrong, ed. Foreign Affairs, 18 Jun 56.  McCloy, Challenge to American Foreign Policy, p. 43. See also Millis, The Forrestal Diaries, pp. 70-71.Page 503
the home islands, that the Joint Chiefs had recommended Soviet entry into the war against Japan.
Soviet participation was a goal long pursued by the Americans.  Both political and military authorities seem to have been convinced from the start that Soviet assistance, conceived in various ways, would shorten the war and lessen the cost. In October 1943, Marshal Stalin had told Cordell Hull, then in Moscow for a conference, that the Soviet Union would eventually declare war on Japan. At the Tehran Conference in November of that year, Stalin had given the Allies formal notice of this intention and reaffirmed it in October 1944. In February 1945, at the Yalta Conference, Roosevelt and Stalin had agreed on the terms of Soviet participation in the Far Eastern war. Thus by June 1945, the Americans could look forward to Soviet intervention at a date estimated as three months after the defeat of Germany.
But by the summer of 1945 the Americans had undergone a change of heart. Though the official position of the War Department still held that "Russian entry will have a profound military effect in that almost certainly it will materially shorten the war and thus save American lives,"  few responsible American officials were eager for Soviet intervention or as willing to make concessions as they had been at an earlier period.  What had once appeared extremely desirable appeared less so now that the war in Europe was over and Japan was virtually defeated. President Truman, one official recalled, stated during a meeting devoted to the question of Soviet policy that agreements with Stalin had up to that time been "a one-way street" and that "he intended thereafter to be firm in his dealings with the Russians."  And at the 18 June meeting of the Joint Chiefs of Staff with the President, Admiral King had declared that "regardless of the desirability of the Russians entering the war, they were not indispensa-
 An excellent official summary of this subject which reproduces the most important documents is The Entry of the Soviet Union Into the War Against Japan. The subject is also well covered in Ernest R. May, "The United States, the Soviet Union, and the Far Eastern War, 1941-1945," Pacific Historical Review (May, 1955), pages 153-74. See also, John R. Deane, The Strange Alliance (New York: Viking Press, 1947); Statement of W. Averell Harriman in MacArthur Hearings, 82d Cong., 1st Sess. (Washington, 1951), Part 5, pp. 3328-42, William H. McNeill, America, Britain, and Russia, Their Cooperation and Conflict, 1941-1946 (New York: Oxford University Press, 1953).  Ltr, Stimson to Grew, 21 May 45, reproduced in Grew, The Turbulent Era, Vol. II. p. 1458, and in The Entry of the Soviet Union Into the War Against Japan, pp. 70-71.  For expressions of this view, see Deane, The Strange Alliance, pp. 263-65; Leahy. I Was There, pp. 318, 339; Byrnes, Speaking Frankly, pp. 207-09; Millis, The Forrestal Diaries, p. 78; King and Whitehill, Fleet Admiral King, p. 606.  Millis, The Forrestal Diaries, p. 50, minute by Charles E. Bohlen dated 23 April 1945, Truman, Year of Decisions, p. 72.
ble and he did not think we should go as far as to beg them to come in."  Though the cost would be greater, he had no doubt "we could handle it alone."
The failure of the Soviets to abide by agreements made at Yalta had also done much to discourage the American desire for further cooperation with them. But after urging Stalin for three years to declare war on Japan, the United States Government could hardly ask him now to remain neutral. Moreover, there was no way of keeping the Russians out even if there had been a will to do so. In Harriman's view, "Russia would come into the war regardless of what we might do." 
A further difficulty was that Allied intelligence still indicated that Soviet intervention would be desirable, if not necessary, for the success of the invasion strategy. In Allied intelligence, Japan was portrayed as a defeated nation whose military leaders were blind to defeat. Though her industries had been seriously crippled by air bombardment and naval blockade and her armed forces were critically deficient in many of the resources of war, Japan was still far from surrender. She had ample reserves of weapons and ammunition and an army of 5,000,000 troops, 2,000,000 of them in the home islands. The latter could be expected to put up a strong resistance to invasion. In the opinion of the intelligence experts, neither blockade nor bombing alone would produce unconditional surrender before the date set for invasion. And the invasion itself, they believed, would be costly and possibly prolonged. 
According to these intelligence reports, the Japanese leaders were fully aware of their desperate situation but would continue to fight in the hope of avoiding complete defeat by securing a better bargaining position. Allied war-weariness and disunity, or some miracle, they hoped, would offer them a way out. "The Japanese believe," declared an intelligence estimate of 30 June, "that unconditional surrender would be the equivalent of national extinction, and there are as yet no indications that they are ready to accept such terms."  It appeared
 The Entry of the Soviet Union Into the War Against Japan, p. 85.  Statement to Leahy quoted in I Was There, p. 369. See also Harriman's statement. MacArthur Hearings, Part 5, p. 3341; War Department memorandum of 21 May 1945. quoted in Grew, The Turbulent Era, Vol. II, p. 1458.  The Entry of the Soviet Union Into the War Against Japan, pp. 85- 88; OPD Study by Brig. Gen. George A. Lincoln, dated 4 June 1945, quoted in Cline, Washington Command Post, p. 344. See also, Leahy, I Was There, pp. 343, 346-47; Stimson, "The Decision To Use the Atomic Bomb," Harper's, pp. 101-02; Willoughby and Chamberlain, MacArthur, 1941-1951, p. 286; Allied Operations in Southwest Pacific Area, GHQ SWPA, I, pp. 397-404.  G-2 Memorandum prepared for OPD and quoted in Cline, Washington Command Post, p. 347. The same study was presented to the Combined Chiefs and is reproduced in part in The Entry of the Soviet Union Into the War Against Japan, pp. 85-88.
also to the intelligence experts that Japan might surrender at any time "depending upon the conditions of surrender" the Allies might offer. Clearly these conditions, to have any chance of acceptance, would have to include retention of the imperial system. 
How accurate were these estimates? Judging from postwar accounts of Japan, they were very close to the truth. Since the defeat at Saipan, when Tojo had been forced to resign, the strength of the "peace army" had been increasing. In September 1944 the Swedish Minister in Tokyo had been approached unofficially, presumably in the name of Prince Konoye, to sound out the Allies on terms of peace. This overture came to nought, as did another the following March. But the Swedish Minister did learn that those who advocated peace in Japan regarded the Allied demand for unconditional surrender as their greatest obstacle. 
The Suzuki Cabinet that came into power in April 19,45 had an unspoken mandate from the Emperor to end the war as quickly as possible. But it was faced immediately with an additional problem when the Soviet Government announced it would not renew the neutrality pact after April 1946. The German surrender in May produced another crisis in the Japanese Government and led, after considerable discussion, to a decision to seek Soviet mediation. But the first approach, made on June 3 to Jacob Malik, the Soviet Ambassador, produced no results. Malik was noncommittal and merely said the problem needed further study. 
At the end of June, the Japanese finally approached the Soviet Government directly through Ambassador Sato in Moscow, asking that it mediate with the Allies to bring the Far Eastern war to an end. In a series of messages between Tokyo and Moscow, which the Americans intercepted and decoded, the Japanese Foreign Office outlined the position of the government and instructed Ambassador Sato to make arrangements for a special envoy from the Emperor who would be empowered to make terms for Soviet mediation. Unconditional surrender, he was told, was completely unacceptable, and time was of the essence. But the Russians, on one pretext and another, delayed their answer until mid-July when Stalin and Molotov left for Potsdam. Thus, the Japanese Government had by then accepted
 Ibid. This view is presented by Karl T. Compton in an article entitled "If the Atomic Bomb Had Not Been Dropped," Atlantic Monthly (December, 1946), pp. 54-60.
 Robert J. C. Butow, Japan's Decision to Surrender (Stanford: Stanford University Press, 1954), pp. 40, 54-57. Other accounts of the situation in Japan are Toshikazu Kase, Journey to the MISSOURI (New Haven: Yale University Press, 1950); U.S. Strategic Bombing Survey, Japan's Struggle To End the War (Washington, 1946); Takushiro Hattori, Complete History of the Greater East Asia War (Japan: Masu Shobo Co., 1953), Vol. IV.  Butow, Japan's Decision to Surrender, pp. 90-91, 125-31; Hattori, Complete History of the Greater East Asia War, Vol. IV, pp. 274, 312-16, USSBS, Japan's Struggle to End the War, pp. 6-7; Kase, Journey to the MISSOURI, pp. 193-94.
defeat and was seeking desperately for a way out; but it was not willing even at this late date to surrender unconditionally, and would accept no terms that did not include the preservation of the imperial system.
Allied intelligence had estimated the situation in Japan correctly. Allied invasion strategy had been re-examined and confirmed in mid- June, and the date for the invasion fixed. The desirability of Soviet assistance had been confirmed also and plans for Russian entry into the war during August could now be made. No decision had been reached on the use of the atomic bomb, but the President's advisers had recommended it. The decision was the President's and he faced it squarely. But before he could make it he would want to know whether the measures already concerted would produce unconditional surrender at the earliest moment and at the lowest cost. If they could not, then he would have to decide whether circumstances warranted employment of a bomb that Stimson had already labeled as "the most terrible weapon ever known in human history."
Though responsibility for the decision to use the atomic bomb was the President's, he exercised it only after careful study of the recommendations of his senior advisers. Chief among these was the Secretary of War, under whose broad supervision the Manhattan Project had been placed. Already deeply concerned over the cost of the projected invasion, the political effects of Soviet intervention, and the potential consequences of the use of the atomic bomb, Stimson sought a course that would avoid all these evils. The difficulty, as he saw it, lay in the requirement for unconditional surrender. It was a phrase that might make the Japanese desperate and lead to a long and unnecessary campaign of attrition that would be extremely costly to both sides.  But there was no way of getting around the term; it was firmly rooted in Allied war aims and its renunciation was certain to lead to charges of appeasement.
But if this difficulty could be overcome, would the Japanese respond if terms were offered? The intelligence experts thought so, and the radio intercepts from Tokyo to Moscow bore them out.  So far as the Army was concerned there was much to be gained by such a course. Not only might it reduce the enormous cost of the war, but
 Stimson, "The Decision To Use the Atomic Bomb," Harper's, p. 102; Cline, Washington Command Post, p. 345; Millis, The Forrestal Diaries, pp. 68-70.  Millis, The Forrestal Diaries, pp. 74-77; Ellis M. Zacharias, Secret Missions (New York: Putnam, 1946), p. 335.
it would also make possible a settlement in the western Pacific "before too many of our allies are committed there and have made substantial contributions toward the defeat of Japan."  In the view of the War Department these aims justified "any concessions which might be attractive to the Japanese, so long as our realistic aims for peace in the Pacific are not adversely affected." 
The problem was to formulate terms that would meet these conditions. There was considerable discussion of this problem in Washington in the spring of 1945 by officials in the Department of State and in the War and Navy Departments. Joseph C. Grew, Acting Secretary of State, proposed to the President late in May that he issue a proclamation urging the Japanese to surrender and assuring them that they could keep the Emperor. Though Truman did not act on the suggestion, he thought it "a sound idea" and told Grew to discuss it with his cabinet colleagues and the Joint Chiefs. On 18 June, Grew was back with the report that these groups favored the idea, but that there were differences on the timing. 
Grew's ideas, as well as those of others concerned, were summarized by Stimson in a long and carefully considered memorandum to the President on 2 July.  Representing the most informed military and political estimate of the situation at this time, this memorandum constitutes a state paper of the first importance. If any one document can be said to provide the basis for the President's warning to Japan and his final decision to use the atomic bomb, this is it.
The gist of Stimson's argument was that the most promising alternative to the long and costly struggle certain to follow invasion was to warn the Japanese "of what is to come" and to give them an opportunity to surrender. There was, he thought, enough of a chance that such a course would work to make the effort worthwhile. Japan no longer had any allies, her navy was virtually destroyed, and she was increasingly vulnerable to air attack and naval blockade. Against her were arrayed the increasingly powerful forces of the Allies, with their "inexhaustible and untouched industrial resources." In these circumstances, Stimson believed the Japanese people would be susceptible to reason if properly approached. "Japan," he pointed out, "is
 OPD Compilation for the Potsdam Conference, quoted in Cline, Washington Command Post, p. 345.  Ibid., pp. 345-46.  Truman, Year of Decisions, pp. 416-17. A detailed account of Grew's efforts can be found in Grew, The Turbulent Era, Vol. II, Chapter XXXVI.  The memorandum is reproduced in Stimson, "The Decision To Use the Atomic Bomb," Harper's, pp. 102-04. For the background of the memorandum, see Grew, The Turbulent Era, Vol. II, Ch. XXXVI; Millis, The Forrestal Diaries, pp. 68-70; Byrnes, Speaking Frankly,pp. 206, 262; McCloy, Challenge to American Foreign Policy, pp. 42-43; Stimson and Bundy, On Active Service, p. 624.
not a nation composed of mad fanatics of an entirely different mentality from ours. On the contrary, she has within the past century shown herself to possess extremely intelligent people...." But any attempt, Stimson added, "to exterminate her armies and her population by gunfire or other means will tend to produce a fusion of race solidity and antipathy...."
A warning to Japan, Stimson contended, should be carefully timed. It should come before the actual invasion, before destruction had reduced the Japanese "to fanatical despair," and, if the Soviet Union had already entered the war, before the Russian attack had progressed too far.  It should also emphasize, Stimson believed, the inevitability and completeness of the destruction ahead and the determination of the Allies to strip Japan of her conquests and to destroy the influence of the military clique. It should be a strong warning and should leave no doubt in Japanese minds that they would have to surrender unconditionally and submit to Allied occupation.
The warning, as Stimson envisaged it, had a double character. While promising destruction and devastation, it was also to hold out hope to the Japanese if they heeded its message. In his memorandum, therefore, Stimson stressed the positive features of the warning and recommended that it include a disavowal of any intention to destroy the Japanese nation or to occupy the country permanently. Once Japan's military clique had been removed from power and her capacity to wage war destroyed, it was Stimson's belief that the Allies should withdraw and resume normal trade relations with the new and peaceful Japanese Government. "I personally think," he declared, "that if in saying this we should add that we do not exclude a constitutional monarchy under the present dynasty, it would substantially add to the chance of acceptance."
Not once in the course of this lengthy memorandum was mention made of the atomic bomb. There was no need to do so. Everyone concerned understood clearly that the bomb was the instrument that, by its powers of destruction, would impress on the Japanese Government the hopelessness of any course but surrender. As Stimson expressed it, the atomic bomb was "the best possible sanction," the single weapon that would convince the Japanese "of our power to destroy the empire." 
 In his diary, under the date 19 June, Stimson wrote: "The last- chance warning ... must be given before an actual landing of the ground forces in Japan, and fortunately the plans provide for enough time to bring in the sanctions to our warning in the shape of heavy ordinary bombing attack and an attack of S-1 [the atomic bomb]." Stimson and Bundy, On Active Service, p. 624.  Stimson, The Decision To Use the Atomic Bomb," Harper's, pp. 101, 104.
Though Stimson considered a warning combined with an offer of terms and backed up by the sanction of the atomic bomb as the most promising means of inducing surrender at any early date, there were other courses that some thought might produce the same result. One was continuation and intensification of air bombardment coupled with surface and underwater blockade. This course had already been considered and rejected as insufficient to produce surrender, though its advocates were by no means convinced that this decision was a wise one. And Stimson himself later justified the use of the bomb on the ground that by 1 November conventional bombardment would have caused greater destruction than the bomb. This apparent contradiction is explained by the fact that the atomic bomb was considered to be capable of a psychological effect entirely apart from the damage wrought. 
Nor did Stimson, in his memorandum, consider the effect of the Soviet Union's entry into the war. By itself, this action could not be counted on to force Japan to capitulate, but combined with bombardment and blockade it might do so. At least that was the view of Brig. Gen. George A. Lincoln, one of the Army's top planners, who wrote in June that "probably it will take Russian entry into the war, coupled with a landing, or imminent threat of landing, on Japan proper by us, to convince them [the Japanese] of the hopelessness of their position." 
Why, therefore, was it not possible to issue the warning before a Soviet declaration of war against Japan and rely on that event, together with an intensified air bombardment, to produce the desired result? If together they could not secure Japan's surrender, would there not still be time to use the bomb before the scheduled invasion of Kyushu in November? 
No final answer to this question is possible with the evidence at hand. But one cannot ignore the fact that some responsible officials feared the political consequences of Soviet intervention and hoped that ultimately it would prove unnecessary. This feeling may unconsciously have made the atom bomb solution more attractive than it might otherwise have been.  Some officials may have believed, too, that the bomb could be used as a powerful deterrent to Soviet ex-
 Ibid., p. 105.  Quoted in Cline, Washington Command Post, p. 344.  For an exposition of this view, see Blackett, Fear, War, and the Bomb, p. 136; Hanson W. Baldwin, Great Mistakes of the War (New York: Harper & Brothers, 1950), pp. 100-101.  See for example, Byrnes, Speaking Frankly, p. 208; Stimson and Bundy, On Active Service, p. 637; Leahy, I Was There, p. 419, Blackett, Fear, War, and the Bomb, Ch. X; Norman Cousins and Thomas K. Finletter, "A Beginning for Sanity," Saturday Review of Literature, XXIX, No. 4 (June 15, 1946), 5-8.Page 510
pansion in Europe, where the Red tide had successively engulfed Rumania, Bulgaria, Jugoslavia, Czechoslovakia, and Hungary. In an interview with three of the top scientists in the Manhattan Project early in June, Mr. Byrnes did not, according to Leo Szilard, argue that the bomb was needed to defeat Japan, but rather that it should be dropped to "make Russia more manageable in Europe." 
It has been asserted also that the desire to justify the expenditure of the two billion dollars spent on the Manhattan Project may have disposed some favorably toward the use of the bomb. Already questions had been asked in Congress,  and the end of the war would almost certainly bring on a full-scale investigation. What more striking justification of the Manhattan Project than a new weapon that had ended the war in one sudden blow and saved countless American lives? "It was my reaction," wrote Admiral Leahy, "that the scientists and others wanted to make this test because of the vast sums that had been spent on the project. Truman knew that, and so did other people involved." 
This explanation hardly does credit to those involved in the Manhattan Project and not even P. M. S. Blackett, one of the severest critics of the decision to use the bomb, accepted it. "The wit of man," he declared, "could hardly devise a theory of the dropping of the bomb, both more insulting to the American people, or more likely to lead to an energetically pursued Soviet defense policy." 
But even if the need to justify these huge expenditures is discounted-and certainly by itself it could not have produced the decision-the question still remains whether those who held in their hands a weapon thought capable of ending the war in one stroke could justify withholding that weapon. Would they not be open to criticism for failing to use every means at their disposal to defeat the enemy as quickly as possible, thereby saving many American lives?
And even at that time there were some who believed that the new weapon would ultimately prove the most effective deterrent to war yet produced. How better to outlaw war forever than to demonstrate the tremendous destructive power of this weapon by using it against an actual target?
By early July 1945 the stage had been set for the final decision,
 Szilard, "A Personal History of the Atomic Bomb," pp. 14-15.  Byrnes, Speaking Frankly, pp. 257-58; Hillman, Mr. President, p. 247. The Truman Committee had already made inquiries, but its investigators were called off at the request of Mr. Stimson. Truman, Year of Decisions, p. 10.  Leahy, I Was There, p. 441. For a statement of the same argument, but with a refutation, see "Report of the Committee on Social and Political Implications," 11 June 1945, Bulletin of Atomic Scientists (May 1, 1946), Vol. I, No. 10, p. 4.  Blackett, Fear, War, and the Bomb, p. 138.
Stimson's memorandum had been approved in principle and on July 4 the British had given their consent to the use of the bomb against Japan.  It remained only to decide on the terms and timing of the warning. This was the situation when the Potsdam Conference opened on 17 July, one day after the bomb had been successfully exploded in a spectacular demonstration at Alamogordo, New Mexico. The atomic bomb was a reality and when the news reached Potsdam it aroused great excitement among those who were let in on the secret. Instead of the prospect of long and bitter months of fighting the Japanese, there was now a vision, "fair and bright indeed it seemed" to Churchill, "of the end of the whole war in one or two violent shocks." 
President Truman's first action was to call together his chief advisers-Byrnes, Stimson, Leahy, Marshall, King, and Arnold. "I asked for their opinion whether the bomb should be used," he later wrote. The consensus was that it should.  Here at last was the miracle to end the war and solve all the perplexing problems posed by the necessity for invasion. But because no one could tell what effect the bomb might have "physically or psychologically," it was decided to proceed with the military plans for the invasion.
No one at this time, or later in the conference, raised the question of whether the Japanese should be informed of the existence of the bomb. That question, it will be recalled, had been discussed by the Scientific Panel on 16 June and at the White House meeting with the Joint Chiefs of Staff, the service Secretaries, and Mr. McCloy on 18 June. For a variety of reasons, including uncertainty as to whether the bomb would work, it had been decided that the Japanese should not be warned of the existence of the new weapon. The successful explosion of the first bomb on 17 July did not apparently outweigh the reasons advanced earlier for keeping the bomb a secret; and evidently none of the men involved thought the question needed to be reviewed. The Japanese would learn of the atomic bomb only when it was dropped on them.
The secrecy that had shrouded the development of the atomic bomb was torn aside briefly at Potsdam, but with no visible effect. On
 Churchill, Triumph and Tragedy, p. 639. For the coordination between the British and Americans on the development of the atomic bomb, see Smyth, Atomic Energy for Military Purposes, passim; Winston S. Churchill, The Hinge of Fate (Boston: Houghton Mifflin Company, 1950), pp. 377-81; Truman, Year of Decisions, p. 418; Leahy, I Was There, pp. 265, 432. General Groves opposed this coordination and so testified later. Oppenheimer Hearings, p. 175.  Churchill, Triumph and Tragedy, p. 638.  Hillman, Mr. President, p. 248; Truman, Year of Decisions, p. 415. General Eisenhower was at Potsdam and his advice, Truman says, was asked. The various participants differ in their recollections of this meeting. King and Whitehill, Fleet Admiral King, p. 621; Arnold, Global Mission, p. 585.
24 July, at the suggestion of his chief advisers, Truman informed Marshal Stalin "casually" that the Americans had "a new weapon of unusual destructive force." "The Russian Premier," he recalled, "showed no special interest. All he said was that he was glad to hear it and hoped we would make 'good use of it against the Japanese.' "  One cannot but wonder whether the marshal was preoccupied at the moment or simulating a lack of interest.
On the military side, the Potsdam Conference developed nothing new. The plans already made were noted and approved. Even at this late stage the question of the bomb was divorced entirely from military plans and the final report of the conference accepted as the main effort the invasion of the Japanese home islands. November 15, 1946, was accepted as the planning date for the end of the war against Japan. 
During the conference, Stalin told Truman about the Japanese overtures-information that the Americans already had. The marshal spoke of the matter also to Churchill, who discussed it with Truman, suggesting cautiously that some offer be made to Japan. "Mr. Stimson, General Marshall, and the President," he later wrote, "were evidently searching their hearts, and we had no need to press them. We knew of course that the Japanese were ready to give up all conquests made in the war." That same night, after dining with Stalin and Truman, the Prime Minister wrote that the Russians intended to attack Japan soon after 8 August-perhaps within two weeks of that date.  Truman presumably received the same information, confirming Harry Hopkins' report of his conversation with Stalin in Moscow in May. 
All that remained now was to warn Japan and give her an opportunity to surrender. In this matter Stimson's and Grew's views, as outlined in the memorandum of 2 July, were accepted, but apparently on the advice of the former Secretary of State Cordell Hull it was decided to omit any reference to the Emperor.  Hull's view, solicited by Byrnes before his departure for Potsdam, was that the proposal smacked of appeasement and "seemed to guarantee continuance not
 Truman, Year of Decisions, p. 416. See also Byrnes, Speaking Frankly, p. 263.  Combined Chiefs of Staff Report to the President and Prime Minister, 24 July 1945, quoted in Cline, Washington Command Post, p. 346, and reproduced in The Entry of the Soviet Union Into the War Against Japan, pp. 89-91.  Truman, Year of Decisions, p. 306; Churchill, Triumph and Tragedy, p. 642. See also Byrnes, Speaking Frankly, p. 205; Leahy, I Was There, p. 420.  Robert E. Sherwood, Roosevelt and Hopkins: An Intimate History (New York: Harper & Brothers, 1948), p. 902, Leahy, I Was There, p. 383.  Cordell Hull, The Memoirs of Cordell Hull, 2 vols. (New York: The Macmillan Company, 1948), II, pp. 1591-94; Byrnes, Speaking Frankly, pp. 205-07; Stimson and Bundy, On Active Service, pp. 626-27; Grew, The Turbulent Era, II, pp. 1424-27.
only of the Emperor but also of the feudal privileges of a ruling caste." And, should the Japanese reject the warning, the proposal to retain the imperial system might well encourage resistance and have "terrible political repercussions" in the United States. For these reasons he recommended that no statement about the Emperor be made until "the climax of Allied bombing and Russia's entry into the war."  Thus, the final terms offered to the Japanese in the Potsdam declaration on 26 July made no mention of the Emperor or of the imperial system. Neither did the declaration contain any reference to the atom bomb but simply warned the Japanese of the consequences of continued resistance.  Only those already familiar with the weapon could have read the references to inevitable and complete destruction as a warning of atomic warfare. 
The receipt of the Potsdam Declaration in Japan led to frantic meetings to decide what should be done. It was finally decided not to reject the note but to await the results of the Soviet overture. At this point, the military insisted that the government make some statement to the people, and on 28 July Premier Suzuki declared to the press that Japan would ignore the declaration, a statement that was interpreted by the Allies as a rejection. 
To the Americans the rejection of the Potsdam Declaration confirmed the view that the military clique was still in control of Japan and that only a decisive act of violence could remove it. The instrument for such action lay at hand in the atomic bomb; events now seemed to justify its use. But in the hope that the Japanese might still change their minds, Truman held off orders on the use of the bomb for a few days. Only silence came from Tokyo, for the Japanese were waiting for a reply from the Soviet Government, which would not come until the return of Stalin and Molotov from Potsdam on 6 August. Prophetically, Foreign Minister Togo wrote Sato on 2 August, the day the Potsdam Conference ended, that he could not afford to lose a single day in his efforts to conclude arrangements with the Russians "if we were to end the war before the assault on our mainland."  By that time, President Truman had already decided on the use of the bomb.
 Hull, Memoirs, II, p. 1593.  The text of the declaration is printed in Stimson and Bundy, On Active Service, and in Butow, Japan's Decision to Surrender, Appendix C.  For expressions of this view, see Baldwin, Great Mistakes of the War, pp. 91-92; McCloy, Challenge to American Foreign Policy, p. 43.  This incident has given rise to a controversy best understood by a linguist. It is covered in detail in Kazuo Kawaii, "Mokusatsu," Pacific Historical Review (November, 1950), pp. 409-14; and William J. Coughlin, "The Great Mokusatsu," Harper's Magazine, (March, 1953), pp. 31-40.  Kase, Journey to the Missouri, p. 222.
Preparations for dropping the two atomic bombs produced thus far had been under way for some time. The components of the bombs had been sent by cruiser to Tinian in May and the fissionable material was flown out in mid-July. The B-29's and crews were ready and trained, standing by for orders, which would come through the Commanding General, U.S. Army Strategic Air Forces in the Pacific, Lt. Gen. Carl A. Spaatz. Detailed arrangements and schedules were completed and all that was necessary was to issue orders. 
At General Arnold's insistence, the responsibility for selecting the particular target and fixing the exact date and hour of the attack was assigned to the field commander, General Spaatz. In orders issued on 25 July and approved by Stimson and Marshall, Spaatz was ordered to drop the "first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki." He was instructed also to deliver a copy of this order personally to MacArthur and Nimitz. Weather was the critical factor because the bomb had to be dropped by visual means, and Spaatz delegated to his chief of staff, Maj. Gen. Curtis E. LeMay, the job of deciding when the weather was right for this most important mission.
From the dating of the order to General Spaatz it has been argued that President Truman was certain the warning would be rejected and had fixed the date for the bombing of Hiroshima even before the issuance of the Potsdam Declaration.  But such an argument ignores the military necessities. For operational reasons, the orders had to be issued in sufficient time "to set the military wheels in motion." In a sense, therefore, the decision was made on 25 July. It would stand unless the President changed his mind. "I had made the decision," wrote Truman in 1955. "I also instructed Stimson that the order would stand unless I notified him that the Japanese reply to our ultimatum was acceptable."  The rejection by the Japanese of the Potsdam Declaration confirmed the orders Spaatz had already received.
On Tinian and Guam, preparations for dropping the bomb had been completed by 3 August. The original plan was to carry out the
 For an account of these preparations, see Craven and Cate, The Army Air Forces in World War II, Vol. V, pp. 713-25.  Ibid., p. 714. The relevant documents, including a letter from President Truman to Professor Cate, are reproduced on pages 696-97, 712- 13. See also Leahy, I Was There, pp. 430-31, and Truman's letter to Dr. Karl T. Compton, published in Atlantic Monthly, (February, 1947), p. 27.  Truman, Year of Decisions, pp. 420-21.
operation on 4 August, but General LeMay deferred the attack because of bad weather over the target. On 5 August the forecasts were favorable and he gave the word to proceed with the mission the following day. At 0245 on 6 August, the bomb-carrying plane was airborne. Six ad a half hours later the bomb was released over Hiroshima, Japan's eighth largest city, to explode fifty seconds later at a height of about 2,000 feet. The age of atomic warfare had opened. 
Aboard the cruiser Augusta on his way back to the United States, President Truman received the news by radio. That same day a previously prepared release from Washington announced to the world that an atomic bomb had been dropped on Hiroshima and warned the Japanese that if they did not surrender they could expect "a rain of ruin from the air, the like of which had never been seen on this earth." 
On 7 August, Ambassador Sato in Moscow received word at last that Molotov would see him the next afternoon. At the appointed hour he arrived at the Kremlin, full of hope that he would receive a favorable reply to the Japanese proposal for Soviet mediation with the Allies to end the war. Instead he was handed the Soviet declaration of war, effective on 9 August.  Thus, three months to the day after Germany's surrender, Marshal Stalin had lived up to his promise to the Allies.
Meanwhile, President Truman had authorized the use of the second bomb-the last then available. The objective was Kokura, the date 9 August. But the plane carrying the bomb failed to make its run over the primary target and hit the secondary target, Nagasaki, instead.  The next day Japan sued for peace.
The close sequence of events between 6 and 10 August, combined with the fact that the bomb was dropped almost three months before the scheduled invasion of Kyushu and while the Japanese were trying desperately to get out of the war, has suggested to some that the bombing of Hiroshima had a deeper purpose than the desire to end the war quickly. This purpose, it is claimed, was nothing less than a desire to forestall Soviet intervention in the Far Eastern war. Else why this necessity for speed? Certainly nothing in the military situation
 Two other dates can be said to have opened the atomic age: 2 December 1942, when Enrico Fermi succeeded in establishing a chain reaction; and 16 July 1945, when the test bomb was exploded in New Mexico.  For a vivid account of the bombing, see Miller and Spitzer, We Dropped the A-Bomb and Laurence, Dawn Over Zero, pp. 207-11. The statement is published in The New York Times, August 7, 1945. See also, Leahy, I Was There, p. 430, and Byrnes, Speaking Frankly, p. 209.  Butow, Japan's Decision to Surrender, pp. 153-54; The New York Times, August 9, 1945.  Craven and Cate, The Army Air Forces in World War II, Vol. V, pp. 714-23; Laurence, Dawn Over Zero, pp. 228-43; Miller and Spitzer, We Dropped the A-Bomb, pp. 89-124.
seemed to call for such hasty action. But if the purpose was to fore- stall Soviet intervention, then there was every reason for speed. And even if the Russians could not be kept out of the war, at least they would be prevented from making more than a token contribution to victory over Japan. In this sense it may be argued that the bomb proved a success, for the war ended with the United States in full control of Japan. 
This theory leaves several matters unexplained. In the first place, the Americans did not know the exact date on which the Soviet Union would declare war but believed it would be within a week or two of 8 August. If they had wished to forestall a Soviet declaration of war, then they could reasonably have been expected to act sooner than they did. Such close timing left little if any margin for error. Secondly, had the United States desired above everything else to keep the Russians out, it could have responded to one of the several unofficial Japanese overtures, or made the Potsdam Declaration more attractive to Japan. Certainly the failure to put a time limit on the declaration suggests that speed was not of the essence in American calculations. Finally, the date and time of the bombing were left to Generals Spaatz and LeMay, who certainly had no way of knowing Soviet intentions. Bad weather or any other untoward incident could have delayed the attack a week or more.
There is reason to believe that the Russians at the last moved more quickly than they had intended. In his conversations with Harry Hopkins in May 1945 and at Potsdam, Marshal Stalin had linked Soviet entry with negotiations then in progress with Chinese representatives in Moscow.  When these were completed, he had said, he would act. On 8 August these negotiations were still in progress.
Did the atomic bomb accomplish its purpose? Was it, in fact, as Stimson said, "the best possible sanction" after Japan rejected the Potsdam Declaration? The sequence of events argues strongly that it was, for bombs were dropped on the 6th and 9th, and on the 10th Japan surrendered. But in the excitement over the announcement of the first use of an atomic bomb and then of Japan's surrender, many overlooked the significance of the Soviet Union's entry into the war on the 9th. The first bomb had produced consternation and confusion among the leaders of Japan, but no disposition to surrender. The Soviet declaration of war, though not entirely unexpected, was a devastating blow and, by removing all hope of Soviet mediation, gave
 Blackett, Fear, War, and the Bomb, p. 137. Norman Cousins and Thomas K. Finletter take the same position in the article, "A Beginning for Sanity."  Sherwood, Roosevelt and Hopkins, p. 902; Edward R. Stettinius, Roosevelt and the Russians (Garden City, N.Y.: Doubleday and Company, 1949), p. 91.Page 517
the advocates of peace their first opportunity to come boldly out into the open. When Premier Suzuki arrived at the palace on the morning of the 9th, he was told that the Emperor believed Japan's only course now was to accept the Potsdam Declaration. The militarists could and did minimize the effects of the bomb, but they could not evade the obvious consequences of Soviet intervention, which ended all hope of dividing their enemies and securing softer peace terms. 
In this atmosphere, the leaders of Japan held a series of meetings on 9 August, but were unable to come to an agreement. In the morning came word of the fate of Nagasaki. This additional disaster failed to resolve the issues between the military and those who advocated surrender. Finally the Emperor took the unprecedented step of calling an Imperial Conference, which lasted until 3 o'clock the next morning. When it, too, failed to produce agreement the Emperor told his minister that he wished the war brought to an end. The constitutional significance of this action is difficult for Westerners to comprehend, but it resolved the crisis and produced in the cabinet a formal decision to accept the Potsdam Declaration, provided it did not prejudice the position of the Emperor.
What finally forced the Japanese to surrender? Was it air bombardment, naval power, the atomic bomb, or Soviet entry? The United States Strategic Bombing Survey concluded that Japan would have surrendered by the end of the year, without invasion and without the atomic bomb.  Other equally informed opinion maintained that it was the atomic bomb that forced Japan to surrender. "Without its use," Dr. Compton asserted, "the war would have continued for many months."  Admiral Nimitz believed firmly that the decisive factor was "the complete impunity with which the Pacific Fleet pounded Japan," and General Arnold claimed it was air bombardment that had brought Japan to the verge of collapse.  But Maj. Gen. Claire L. Chennault, wartime air commander in China, maintained that Soviet entry into the Far Eastern war brought about the surrender of Japan and would have done so "even if no atomic bombs had been dropped." 
 The story of the last few days of the war in Japan is told in considerable detail in Butow, Japan's Decision to Surrender; USSBS, Japan's Struggle To End the War; USAAF, Mission Accomplishe (Washington, 1946). On the American side, the chief sources are Byrnes, Speaking Frankly, pp. 209-11; Leahy, I Was There, pp. 434-45; Millis, The Forrestal Diaries, pp. 82-85; Stimson and Bundy, On Active Service, pp. 626-67, Deane, The Strange Alliance, pp. 277-78.  USSBS, Japan's Struggle To End the War, p. 13. See also Arnold, Global Mission, p. 598.  Dr. Karl T. Compton, "If the Atomic Bomb Had Not Been Dropped," Atlantic Monthly (December, 1946), p. 54.  Arnold, Global Mission, p. 598. Nimitz' statement is quoted in Baldwin, Great Mistakes of the War, p. 93.  The New York Times, August 15, 1945, quoting an interview with Chennault.Page 518
It would be a fruitless task to weigh accurately the relative importance of all the factors leading to the Japanese surrender. There is no doubt that Japan had been defeated by the summer of 1945, if not earlier. But defeat did not mean that the military clique had given up; the Army intended to fight on and had made elaborate preparations for the defense of the homeland. Whether air bombardment and naval blockade or the threat of invasion would have produced an early surrender and averted the heavy losses almost certain to accompany the actual landings in Japan is a moot question. Certainly they had a profound effect on the Japanese position. It is equally difficult to assert categorically that the atomic bomb alone or Soviet intervention alone was the decisive factor in bringing the war to an end. All that can be said on the available evidence is that Japan was defeated in the military sense by August 1945 and that the bombing of Hiroshima, followed by the Soviet Union's declaration of war and the bombing of Nagasaki and the threat of still further bombing, acted as catalytic agents to produce the Japanese decision to surrender. Together they created so extreme a crisis that the Emperor himself, in an unprecedented move, took matters into his own hands and ordered his ministers to surrender. Whether any other set of circumstances would have resolved the crisis and produced the final decision to surrender is a question history cannot yet answer.